Assessment of Some Toxic Effects of Lead Nitrate on Heterobranchus Longifius (Valenciennes, 1840) Fingerlings

Abstract

Some toxic effects of lead nitrate (PbNO3)2 on Heterobranchus fongifilis under laboratory conditions for periods of 42 days were investigated. 300 fingerlings were obtained and acclimatized for 14 days. The acute toxicity test was conducted for 96 hours to determine the LC50. Superoxide Dismutase (SOD) and Lipid Peroxidase (LPO) production levels were determined in the gills, liver and kidneys of the fish exposed to the sub-lethal concentration of (PbN03)2. Four treatments; 27, 41, 54 and 68 mg/L with replicate in each case were taken as 10, 15, 20, 25% of the LC50, respectively. The samples were collected and homogenized in phosphate buffer on 14th, 28th, and 42nd day of exposure. From the results, the LC50 was 272.62 mg/L. The LPO level in gills and SOD activities in liver of H. fongifilis exposed to highest concentration (68 mg/L) of (PbN03)2 was significantly (P<0.05) lower when compared with the control on day 42. There were increased production levels of LPO in liver, gill and kidney on day 28 in all treatments. The gill had the highest production level of LPO (1.1622±0.42) at 54 mg/L on day 28. Liver SOD activities in fish exposed to the lowest concentrations (27 mg/L) of Pb(NO3)2 was significantly different (p<0.05) on day 14 when compared with control and other treatments. The kidney showed the highest activity of SOD at 41 .mg/L on day 28. Fish mortality increased with increased concentration of Pb(NO3)2 during acute toxicity test. The toxic effects of Pb(NO3)2 on H. longifilis manifested in physical and behavioural changes in both acute and sub-lethal exposures of the fish to the toxicant; as well as varying production levels of the antioxidants (SOD and LPO) and can therefore, be used for early detection of the effects of pollutants in aquatic environment.